Telephone-exchange system



Filed Oct. I16 1920 4 Sheets-Sheet 1` Sept. 2 19.24.` '1,506,743

J. GOODERHAM TELEPHONE EXCHANGE SYSTEM Filed oct. 1e. 1920 4sheetsfsheqt 2 (/0/7/7 ifi/ @oder/7am.

Sept.- 2 1924.

J. w. GooDERl-IAM TELEPHONE' E'XCHMIGE SYSTEM 1920 4 SheetS-Sbeet 5Fuer; oct. 15

Sem., 2, 1924.

J. W. GOODERHAM TELEPHONE EXCHANGE SYSTEM Filed Oct. 16 '1920 4SheeS-Sheet 4 r IKE@ /H vena/1 Jah/7 VV Gaaaerdm.

Patented Sept.. 2, 1925i@ UNITED STA'E'ES JOHN W. GOODERHAM, 0F NEVIYORK, l\T. Y..

IPANY, INCORPORATED, Of? YORK.

escena @FFHCEQ liiiprovenients in Telephone-Exchange Systems, oit whichthe following is a full, clear, concise, and enact description.

This invention relates to a telephone exchange system in whichconnections are established throuefh the medium of mechanical switchingTdevices, and more particularly to means whereby a subscriber in anexchange of this character may become connected to a distant exchangethrough a toll switching center.

In otlices in which connections in the local area are established bymechanical switch devices without the services of a central oiiceoperator, it is customary to provide special operatoi"s positions in thetull mechanical ottico with which subscribers may become connected hydialingr a single dioit O 'lor the purpose of ygiving the subscribersspecial service and tor extendingtoll connections. In my rio-pendingapplication, Serial N 417,421, liled on even date, l have disclosed onemethod which may be ein ployed in extending toll connections troni aliull n'iechanical oflicc to a distant exchange, employing a tollrecording trunk extending to a toll switching' center ot the originatingexchange, from which center the connection may be tui-ther extended inthe usual inanner over a toll trunk to a toll position ot the distantexchange. i

This method off extending toll connections is quite satisfactory torshort haul tratlic, that is, where the exchangesare not widely separatedand no greatlapse of time intervenes between the extension ot' the tollconnection by the special operator to the toll switching center, and thesuccessful er;- ten-sion of the connection Vtroni the switching centerto the Eine ot the desired subscriber in the distant exchange. it,however, the exchanges are widely separated and the tratlic between themis heavy, th re may be considerable delay before the toll operator atthe switching centercan obtain Serial No. 417,422.

an assigi'inient ot a toll trunk and a connecthrong'h distant exchangeto the de- 'I 1 line, Tfilliewe there is such considerable init is notdesirable to maintain the operator in on the connection and ei byprevent the use of her cord and disselector tor extending otherconnecohviae this dithculty, it is a feature of this invention toprovide a holding cord at the special operators position by means ofisnicli she inay hold the connection extendingl to the callingsubscribei"s line while she proceeds to ti' `.ster the call to the tollswitching' center and while the toll operator at the toll switching;`center is obtaining the desired connection, thereby permittingV her ttalrc `ilown the cord circuit by means of 1which she initialljifanswered the call. rlhe molding cord il" single ended and terminates nalselector switch ot the `lall ncciii iical o'zicc and is accessible fromcenter through a cordless `he toll switching;

operators pos't'on and Final selector switch.

i 1. f i il switching to Lei' position.

i i l i T the to operator at the toll btain a connection over the tollcenter may o line to the line ot the desired subscriber in the distantexcliannc, ani connect such line cord to the line of the calling`subscrilici'. Aa this manner the special oi eters time is not consumedwaiting on the Vdelayed establishment ot toll connection c insnpira'ising suoli established toll iccticns, it heiniv tar moreeconomical to iter supervise, such connections to coi'fline' through thenel lin'.f

ction with the calltiunk, the cordless only to establish 'cion throughlier pow, an object of the invention cient means forestablishconnections outgoing from a full which obifiates the unneccialoperators position, the terminals of which are accessible from a tollswitching center through which a revertive connection may be establishedwith the calling line after connection has 'been successfullyestablished with the desired called line.

These and other objects of the invention will be more readily understoodby reference to the accompanying drawings in which Fig. 1 shows aschematic representation of the circuits employed in the establishmentof a toll connection from the line of a subscriber A in the oiiice X,through a toll switching center Y to a subscribers line B in an oflice Zof a distant exchange; Fig. 2 'shows a holding cord associated with thelspecial operators position of the oliice X which terminates in theterminal banks of final selector-switches of the same oiiice; Fig. 3shows the circuits of a final selector switch together with thecontrolling circuits associated therewith. in the terminal bank of whichthe holding cord o f Fig. 2 terminates; and Fig. 4 shows an incomingselector switch at the cordless operators position accessible from thetoll switching center and having access to the circuits of iinalselector switches, together with the controlling circuits associatedtherewith, and a sending mechanism under the control of the cordlessoperator for controlling' said switches, said sending mechanism beingrepresented by the apparatus shown in the dotted rectangle.

1t will be assumed for convenience in disclosing the invention that thesubscribcrs line A terminates in a full mechanical oiiice X of thegeneral type disclosed in the patent to F'. A. Stearn and F. J. Scudder,1,395,977, issued November 1, 1921, and that the called subscribers lineterminates in the office Z of a distant exchange. and that a tollconnection is established 'between the subscribers line through the tollswitching center Y connection with the line of subscriber B in responseto the digits dialed, obtains a connection with the trunk circuit 103extending to a special operators position 0. The special operator, uponanswering the call, ascertains the number and exchange designations ofthe desired line and proceeds to set up the proper routing upon thekeyboard of hen-sending mechanism .104: for setting l the districtselector switch 105, in which her cord circuit 106 terminates, upon theter-- minals of an idle toll trunk 107 extending to the toll switchingcenter Y.

In response to the extension of the connection to the toll switchingcenter Y, an idle operator at such position answers the call with a cordcircuit 108. The special operator at position 0 has, in the mean time,selected an idle holding cord 200 and connected it with the multiples ofthe trunk cir.- cuit 103 for holding the calling line, and now upon theresponse of the toll operator transmits to the toll operator the numberand exchange designation of the desired line and the terminal numberassigned to the holding` cord taken for use and then takes down her cord106 freeing the selector switch 105 and the sender 104 for use inextending other connections.

The toll operator at the switching center Y disconnects the answeringplug of a cord 108 from the trunk line 10,7 and connects it with theYtrunk line 116 extending to the cordless operator-s position 0 of ofliceX and transmits to the cordless operator the number of the holding cord200 which the special operator has employed, and proceeds to obtain theassignment of a toll line extending to the distant exchange. Through thecc-opei'ation of the toll and terminating operators at such exchange shethen obtains a connection with the desired line B.

rllie cordless operator in response to the instructions of the tolloperator then sets up the number of the holding cord upon her sender 117which then causes the setting of the incoming selector switch 4:18, inwhich the trunk line 416 terminates, and the setting of the finalselector switch 350 upon the termina-ls of the holding cord 200. Uponthe extension of a connection between the holding cord and the tolloperators position, the toll operator instructs the calling subscriberto hang up his receiver while awaiting the extension ofthe connection tothe desired line. The calling subscriber A is then signalled, upon thesuccessful extension of the connection and conversation may then takeplace between the subscriber A and subscriber B as soon as subscriber Aresponds to the signal.

The apparatus employed in extending a connection to the toll switchingcenter is identical with Vthat shown and described in my aforesaidco-pending application and since it forms no essential part of thepresent invention has been disclosed only in a schematic manner inFig. 1. K

The holding cord circuit 200 shown in Fig. 2 is of the single plug endedtype terminating in multiple terminals appearing in the banks of iinalselector switches, and is arranged to transfer the supervision of thecalling line from the special operators position to the toll operatorsposition in the toll switching center Y, as scola as the holding cord isconnected to the toll switchlng center.

The selec-tor switches 350 and 418 shown in Figs. 8 and .4, are of thegeneral type disclosed in the patent to Craft and Reynolds No.1,123,696, issued January 5, 1 915` For controlling the circuitsassociated with these switches, auxiliary switches 800 and 400 of thesequence switch type, disclosed in the patent V'to Reynolds and BaldwinNo. 1,127,- 808, issued February 9, 1915, are employed. These switchescomprise switch sha-tts .carrying a plurality oi contact operating cains301 to 316 inclusive and 401 to 415 inclusive respectively, which indifferent angular positions of the switch shaft effect the closure ofthe respective circuits of the selector switches. Canis 301 and 401 aremaster caros and open the contacts associated therewith only in thepositions indicated by the numerals applied vadjacent thereto. `Theremaining cams close their respective contacts only in the positionsindicated by the numerals applied adjacent thereto.

The selector switches 350 and 418 are selectively controlled by anofiice send-ing mechanism, 417 diagr-ainniatically represented by theapparatus enclosed vin'the dotted rectangle inarked sender, shown at thebottoni of Fig. 4. rlf'his sender is of the Well-known type'such as isdisclosed in the patent to Lundell No. 1,168,319 issued J ,anuary 18,191.6 but since it enters only incidentally into the disclosure of thisinvention and fornis no essential part thereof, a schematic disclosurethereof is thought to be sufficient.

The apparatus employed and the general niethod ot' operation of .thesysteni having now been briefly described, a detailed description of theniethod ot establishing a connection will now be given in order tobetter disclose the salient features of the invention. The subscriber Adesiring a toll connection with the subscriber B removes his receiverfrom the switch-hook and in the manne-r previouslydescribed, through theoperation of the vline Yswitch and the district selector switch 101obtains a connection with the trunk circuit 103 extending to a specialoperators position 0.k The special operator in vresponse to the callinserts the plug of a cord circuit 106 fin the jaclr of the trunk 103and ascertains troni the calling subscriber the exchange and numberdesignation o the desired line. It has been as vsuined that thesubscriber desi-red is in an exchange quite distant from the originatingVexchange and to which the tra-Hic is heavy. The special operator atposition 0 tloesinot attempt to establish a direct oo nnection `over therecording trunk '107 and thro-ndlr the toll fsw-itching" center Y, sincecorr'.` lErable time elapse beto-re a suc- 'feSSi-u'l call isvestablished ywith the sul),

scribers line B and it is undesirable to tie up equipment at herposition and the recording trunk 107 during the establishment of theconnection. The operator at position 0 therefore inserts the plug P of aholding cord circuit into a multiple oi' the trunk circuit 103 for thepurposeot' holding the connection between the calling subscribers lineand her position so that she inay take down the connection which sheoriginally vestablished in answering the call.

Upon the insertion ot the plug P in the multiple jack J of the trunkcircuit 103, a circuit isv closed from grounded battery, through thewinding of sleeve relay v201 sleeve contact 202 of the plug P, sleevecontact 203 of the jack J, and thence to ground through the winding ofsleeve relay 20.4 of the trunk circuit 103. Both relays 2 01 and 204energize in this circuit, relay 204 establishing a holding circuitthrough the winding of slow to vrelease relay 27.05 which may be tracedfrom grounded battery, through the winding of relay 205 and thence toground through the armature and front contact of relay 204. Relay 205upon energizing connects ground potential to the sleeve conductor 206 ofthe trunk circuit 103 for the purpose of maintaining the districtselector 101 and the subscriber-s line -f' switch 100 in their operatedpositions so that the calling subscriber may restore his re-v ceiver toits switch-hook while awaiting the establishment ,of the desired tollconnection without causing the release of the connection Ywhich has beenestablished troni his line to the special opcrators position.

Sleeve relay 201 upon energizing closes a circuit tor the supervisorylamp l207, which circuit n'iay be traced from grounded battory through.the lamp 207, lett-hand armature and viront .contact of relay 201, 'thearmature and back Contact of relay 208, and thence to ground at theright hand armatu-r-e and back Contact ,ot relay 200. Lamp 207 does nothowever become illuminated since this Aoperating circuit is immediatelyopened at the armature and back Contact of relay 208, which relaybecomes energized as soon connection is made with the trunk 103. Thecircuit of relay 208 may be traced frein grounded battery, through' therighthand winding of relay 208, inner left-hand armature and backcontact of relay `210, ring conductor 218 of the holding cord circuit200, ring contacts of plug P and jack J and thence over the ringconductor of the trunk lcircuit 10.3 through the lower brushes ofselector switch '101 and switch 100, over the subscribers line loop,through the upper .brushesY .of line switch 100 and selector switch 1.01tip .conductor of trunk 103, tip contacts of ack J :and plug "P, .tipconductor 210 of the cord circuit, the eouter lefthand armetureand hackcontact et relay .210 and thence to ground through the left-hand windingof relay 208. Relay 201 at its right hand armature and Jfront contactcloses a circuit for supervisory lamp 211, extending from groundedbattery through the lamp 211, left-hand armature and back contact ofrelay 209 and thence to ground at the right handarmature and frontcontact of relay 201.

The operator at position upon noting the illumination of lamp 211 throwsher listening key 212 to connect lier telephone set with the strands ofthe holding cord circuit 200. Upon the depression of the listening key212, the contacts 213 associated with the key are closed itorestablishing a circuit for relay 214. This circuit may be traced 'fromgrounded battery through the left-hand winding of relay 214 and thenceto ground through the contacts 213. Relay 214 upon energizingestablishes a locking circuit for itself extending from grounded batterythrough lamp 207, the left-hand armature and front contact of relay 201,

l the armature and front contact of relay 208 and thence to groundthrough the right- Cil hand winding of relay 214.

The operator at position 0 now withdraws the answering plug of the cordcircuit 106 which she has employed to answer the call, and then proceedsthrough the setting of her sender 104 to set the district selector 105of the cord circuit 106 upon the terminals of a recording toll trunk 107eX- tending to vthe toll switching center Y. The operator at the tollswitching center answers the call on the trunk 107 by means of a cordcircuit 108 and receives from the operator at position 0 the exchangeand number of the subscriber desired, the number of the holding trunk200 which the special operator has employed and such other informationin connection withthe call as is necessary to be recorded upon herticket. After having transmitted this information, the operator atposition 0 may then release the apparatus at her position in readinessfor establishing other calls.

The operator at the .toll switching center Y now communicates over anorder wirecircuit (not shown) with the operator at the cordless position0, shown in Fig. 4, and obtains from the cordless operator theassignment of a cordless trunk circuit, suoli as 416, extending fromthe'cordless operators position to the toll switching center, andtransmits to the cordless operator the number of the holding cord 200which she has recorded upon her ticket.

The operator at the toll switching center Y now withdraws the answeringplug of her cord circuit 108 from the answering jack of the trunkcircuit and connects it with the jack of the assigned cordless trunk416. A

circuit is now established over the tip conductor of the trunk circuit,through the upper right hand windingv of repeating coil 419, left-handarmature and Vback Contact of relay 420 and thence to ground throughthe` right hand winding of line relay 421, and a circuit is establishedover the ring conductor of the trunk circuit through the lower righthand winding ofV repeating coil 419, normally closed make contacts of,the

tery through lamp 423, the upper contacts of sequence switch cam 404,left-hand armature and front contact of relay 422 and thence to groundthrough the left-hand coni tacts of sequence switch cam 405.

The operator in response to the signal from lamp 423 operates startingkey 424, it she hasnot already operated it immediately upon theassignment o1 the trunk and before the toll operator has connected withthe cordless trunk 416. The operation oiZ key 424 establishes a circuitfor driving the sequence switch 400 out of position 1 and into position2, this circuit extending from grounded battery, through the drivingmagnet of sequence switch 40,0, lower right-hand contact of sequenceswitch cam 406 and thence to ground through the contact of key 424. Assoon as sequence switch 400 leaves position 1 the circuit of relay 422is opened and the lamp 423 is then maintained lighted over a circuit eX-tending from grounded battery, through the lamp and thence to groundthrough contacts of sequence switch cam 407 until a sender has beenselected and associated with the trunk circuit 416. Y

With sequence switch-400 in position 2, a circuit is established overthe starting conductor 425 for starting up a trunk linder lforassociating the sender 417 with the cordless trunk 416. switch is of theordinary type and has vno direct bearing upon this invention, it has notbeen disclosed.V The starting circuit may be traced from` conductor 425through the lower left-hand contactl of sequence switchcam 408,right-hand armature and back contact of relay 422 and thence-to groundat the lower left-hand contact of sequence kswitch cam-407. As soon' asthe sender selector finds trunk 416, which vtrunk Since thisV selectorGar is marked as in a c alling condition by ground connected to theupper right-hand Contact ot sequence switch cam 409, a circuit isestablished over the conductor 426 for arrestingv the selecting movementof the selector switch. This circuit may be traced 'from ground, throughthe right-hand` contacts ot sequence switch cam 409, lefthand armatureand bacl; contact of relay 422, and thence to the conductor 426 throughthe left-hand contacts or" sequence switch cam 410.

As soon as the sender` is associated with the cordless trunk 416, asequence switch (not shown) but associated with the sender, advances toposition 5 and at its cam 427 closes a circuit for advancing sequenceswitch out ot position` 2 anc into position 3. This circuit may betraced from grounded battery, through the winding of magnet 400, lowerlett-hand contact of sequence switch cam 411 and thence to groundthrough the sequence switch 4cam 427.

is soon as sequence switch. 400 leaves position 2, the circuit overstarting conductor 425 is opened and a circuit is established overconductor 428 for holding "he sender in association with the cordlesstrunk 416. This circuit extends from conductor 423 to `ground throughthe righthand contacts ot sequence switch cam 410. Sequence switch 400upon reaching position 3 closes a circuit for supervisory lamp? 429,extending from grounded battery through lamp 429, lower contactsorsequence switch cam 404 and thence to ground at interrupter 430 andthe lamp 429 thereupon flashes and continues tov dash until selectionhas been completed, Lamp 423 is now eX- tinguished since sequence switch400 opened the circuit ci' this lamp at cam 407 as soon as a sender wasassociated with the cordless trunk 416.

lith sequence switch 400 in position 3 a fundamental circuit isestablished .ein tending through the winding of relay 422v und thewindings o stepping relay 43.1 ot the sender, which circuit may betraced from grounded battery through the le'lt hand ii'inding ot relay422, lower lett-hand Contact ot sequence switch cam 40,2,lower1iglit.-lxand contact of sequence switch cam 403, the windings ofstepping relay 431 and thence to ground through thearmature and backcontact ot relay Relay 422 upon energizing closes a circuit for drivingsequence switch 400 out of position 3 and into position 5, this circuitextending from grounded battery, through the magnet winding ofsequenceswitch 400, upper lefthand contact or sequence switchcam 406,

right-hand armature and front Contact oi relayv 422 and thence to groundat the lettf hand Contact ot sequence switch cani 4047.

As soon as sequence switch 400 leaves position 4, the energizing circuitYpreviously traced for relay 422 is opened at the lower left-'handcontact of sequence switch cam 402, but relay 422 remains locked up tothe fundamental circuit over a circuit extending from grounded batterythrough its lett-hand winding, upper left-hand and lowerright-handeontacts of sequence switch cam 409, left-hand armature andfront contact of relay 422,upper lett-hand contact of sequence switchcam 403 and thence over the fundamental circuit as pre# Viously traced.y l l As soon as sequence switch 40S() reaches position 5, a circuit is4established for the up drive magnet 433which circuit may be traced fromgrounded` battery, through the winding of rmagnet A433, lower lett-handand upper right-hand contacts'r ot sequence switch cani 412,r right-handarmature and fro-nt contact of relay 422 and thence to ground at theleft-hand Contact of sequence switch cam 407. Magnet 433 upon energiz#ingpres'ses the depending: portion vof the sha-tt 434 of selector switch418 against the constantly rotating up drive roller 435,

'thereby causing the switch shaft to move upwardly in its brushselection movement.

During its upward movement' an' intermittent shunt to ground isconnected to the fundamental circuit between the windings of relay 422and of stepping relay 431 for the purpose of counting down the countingrelays of the' sender in accordance with the irst digit of the numberset up on the sender, in the well known manner.- This intermittent shuntis applied to the fundamental circuit over a circuit which may be tracedfrom ground at sequence switch cam 413', conductor 436', brush 43'?,lbrush selection segment 438 of the commutator 439, conductor 440, theupper left-hand Contact of sequence switch cam 402 rand thence toajunction point in the fundamental circuit between the windings otrelays 422 and 431 at sequence switch cam 403. The switch shaft 434continues in its upward movement until the zero counting relay of thesender becomes energized when the relay 432 is energized to open thefundamental circuit.

Upon the opening of the fundamental circuit relay 422 deenergizes,closing at its righthand armature and baclr Contact circuit for drivingsequence'switch l400 out of position 5 into position' 6. This circuitmay be traced from grounded battery through the winding of the drivingmagnet of sequence switch 400', the lowerlett-hand contacts of sequenceswitch caml 406, righthand armature and back contact ot relay 422 andthence to ground at theAlet-hand con-Y tact of sequerfice'y switch cam407, Relay 422 also upon deenergizing opens the circuit of up drivemagnet 433i to arrest the upward movement of the switch shaft. A set ofbrushes, which it will be assumed is the setdisclosed in the drawing, isnow positioned with relation to the tripping spindle to be tripped uponthe. energization of tripping magnet 422 and a subsequent upwardmovement of the switch shaft. As soon as seH quence switch 400 reachesposition 6, the circuit of tripping magnet 442 is completed, extendingfrom grounded battery through the winding of magnet 442 and thence toground through the lower left-hand contact of sequence switch cam 413.

With sequence switch 400 in position 6 the fundamental circuitpreviously traced through the left hand winding of relay 422 and thewindings of stepping relay 431 is again established. Relay 422 uponenergia ing over the fundamental circuit closes a circuit for drivingsequence switch 400 out of position 6 and into position 7, which circuitextends from grounded battery, through the winding of the driving magnetof the sequence switch, the upper left hand contact of sequence switchcam 40G, right hand armature and front contact of relay 422 and thenceto ground at the left hand contact of sequence switch cam 407. As soonas sequence switch 400 leaves position 6 "the initial energizing circuitof relay 422 is opened at the lower left hand contact of sequence switchcam 402, but relay 422 re mains locked to the fundamental circuit overthe locking circuit previously traced. The circuit of the up drivemagnet 433 is now 11e-established and the switch shaft 434 is drivenupwardly in its group selection movement toV position the selected setof brushes in association with the desired group of bank terminals.During the initial portion of thev upward movement of the switch shaftthe selected set of brushes is tripped and thereafter an intermittentground is connected to the fundamental circuit for shunting down thestepping relay 431 of the sender to operate the counting relays of thesender in the well known manner. This shunt circuit may be traced fromground at the upper left hand contact of sequence switch cam 413,conductor 436, brush 443, group selection segment 444 of the commutator439, conductor 445, right hand contact of sequence switch cam 402 andthencetothe fundamental circuit at se quence switch cam 403.

As soon as the switch shaft 434 has moved upwardly to such an extent asto satisfy the setting of the counting relays of the sender, relay 432at the sender becomes energized to open the fundamental circuit, therebycausing the deenergization of relay 422. Relay 422 upon deenergizingopens the circuit of the updrive magnet 433 to arrest the selected set'of brushes in'contact with the lowermostv set of terminals in. theselected group of bank terminals and closes at its right hand armatureand back contact the previously traced circuit'for driving sequenceswitch 400 out of position 7 and into position 8.

Vith sequence switch 400 in position 8, a circuit is established forrelay 422 which 'may be traced from grounded battery,

through the right hand winding of this relay and thence to groundthrough the lower right hand and upper left hand contacts of sequenceswitch cam 405. Relay 422 upon energizing closes a circuit for advancingsequence switch 400 out of position 8 and into position 9, this circuitextending front grounded battery, through the winding of the drivingmagnet of the sequence switch, the upper left hand contact of sequenceswitch cam 406, right hand armature and front contact of relay 422 andthence to ground at the left hand contact of sequence switch 407. Whensequence switch 400 leaves position 8, if the lowermost set of bankterminals in the selected group upon which the tripped set of brushesare arrested are the terminals of an idle trunk, then relay 422-immediately deenergizes thereby preventingl the establishment of acircuit from the up drive magnet 433 when the sequence switch reachesposition 9.

lf, however, the first set of terminals in the selected group are theterminals of a busy trunk, then relay 422 locks up with the sequenceswitch in position 8 over a circuit extending from grounded battery,through the left hand winding of relay 422, the lower left hand contactof sequence switch cam 402, upper left hand contact of sequence switchcam 403, the left hand armature and front contact of relay 422, lowercontacts of sequence switch cam 409, test brush 446A and thence toground at the test terminal 447 of the first busy trunk of the selectedgroup. rlhis locking circuit is maintained after sequence switch 400.reaches position 9 and therefore with sequence switch 400 in position 9and relay 422 energized, a circuit is established for updrive magnet 433which. may be traced from grounded battery, through the winding ofmagnet 433, lower left hand and upper right hand contacts of sequenceswitch cam 412, right hand armature and front contact of relay 422 andto ground at the left hand contact of sequence switch 407. In responseto the energization of the up drive magnet 433, switch shaft 434is'driven upwardly in its limiting movement or until the test brush 446encounters the test terminal of an idle trunk leading to an idle finalselector switch.

it will be assumed that the first idle trunk encountered is the trunkshown which terminates in the bank terminals 443, 449 and 450, and thattherefore relay 422 is maintained locked up until thetest brushl 44e,encaminan test terminal `ne er this trunk. As' 'seen as ennecticn isniade ywith this idle trunk, the leiing ei'ciiit 'ef relay 422 is openedand relay 422 deen'egi'zes felioeing the Center-ing or the brushes 44e,451 and 452 upon the terminals 448, 449 and 450, relay 422 beingmaintained energized until the brushes are properly centered ever acentering locking circuit extending frein grounded battery, through itsright hand winding, the right hand eitactssequence switch cai-n 405,ce-'ndiicter 453,*eeiitering segment 454 of cein'niutator 439,-hrush'455, upper contacts et sequence switch cam 412, right hand armature andfront eontact of re# lay 422 and theiice t'o griind at the left handcontact of sequeice switch cam 407. Upea the deeergization er, 'relay422, the circuit 'of up drive magnet 433 is ope-ned to arrest the upwardiiioveiieiit of the s'witeh shaft and a circuit is established frdriving sequence switch 400 out of psitien 9 and into position 11, thiscircuit entendin'g from grounded battery, through the winding f thedriving magnet of the sequence switch, the lower lei't hand cntact ofsequence switch cani 406, right hand armature and hack contact yof'relay 422 and thence to ground at the left hand Contact ef sequenceswitch c'ain 407. i

lith sequence switch 400 in position 11, a circuit is established forplacing a busy potential upon the test terminal 448 of the selectedtrunk circuit, 'extending from ground at the upper right hand Contact ofVsequence switch cani 409, the lower lei't hand contact of lcam 409, andthence thr'enfgh test brush 446 to-the test terminal l448. The`fundamental circuit is new diseas'scciated from the relay 422 of theselector switch 418 and is extended Iover the lower right hand and upperlett hand contacts of sequence switch cani 414`r hrnsh 452, bankterminal 450, conductor 317, lower lright hand Contact oit' sequenceswitch cam 302, lower right hand contact of sequence switch cam 303,through the left hand winding of line relay 3518 yot the tinal selectorswitch 350 and thence to grounded battery through 'the right handContact 'of sequence switch cam 304. At the lower contact `of sequenceswitch cam 415, the advance lead 456 is extended from the sender overvthe brush '451 and bank terminal 449 'ot the selector yswitch 418 tothe trunk conductor 319 and lthence through the upe per right hand 'andlower left hand 'contact-s ot sequence switch cam 305, throughyresistance element 320 'to ground at the lower right hand contact ofsequence switch 'cam 306 for a purpose to he later described. Y

Upon the Aextension of the fundamental circuit to the hnal selectorswitch 350, relay 318 'of the lfinal selector .'switch `and steppingrelay 431 of the ysender energize. Relay 318 closes a circuit for relay321 which be traced from grounded battery through the right hand windingof relay 321, conductor 322, vupper right hand Contact of sequenceswitch cam 307, c'onduci tor 323, right hand armature and front con*-tact of relay 318 and thence to ground through the upper contact ofsequence switch cam 308. Relay 321 energizes in this circuit and at itsright hand armature and front contact closes a locking circuit foritself extending from grounded battery through its right hand winding,the armature and hack contact of test relay 324, right hand armature andfront Contact of relay 321, sleeve conductor 325, bank terminal 448, andbrush 446 of the incoming selector switch 418 and thence to ground atsequence switch cam 409. Relay 321 upon energizing closes a circuit fordriving sequence switch 300 out of normal position 1 into positicn 2,which circuit may he traced from grounded battery through the winding ofthe driving magnet of sequence switch 300, the lower contacts ofsequence switch cani 309 and thence to ground at the lett hand armatureand front contact of relay 321. lhen sequence switch 300 moves out ofposition 1, the initial energizing circuit of relay 318 is opened at thelower right hand contact of sequence switch cam 303, -hut relay 318 re-.i

mains energized over the fundamental rcircuit hy reason `of a lockingcircuit extending from grounded battery through the right hand Contactof sequence switch cam 304, left hand winding of relay 318, lower lefthand contact of sequence switch cam 310, left hand armature and frontContact of relay 318, lower left hand contact of sequence switch cam 303and thence through the lower right hand contact of sequence switch cam302 and over the fundamental circuit as previously traced.

Relay 318 upon energizing, with sequence 300 in position 2, closes acircuit tor the high speed up drive magnet 326 which circuit may hetraced iro-m grounded hattery through the winding of magnet 328, theupper left hand contact of sequence switch cam 311, conductor 323, righthand armature and front Contact of relay 318 and thence toiA ground atthe upper right hand contact of sequence switch cam 308. Magnet A326upon energizing presses the depending portion ot switch shaft 327against the constantly rotating high speed roller 328 thereby Icausingthe switch shaft to he moved upwardly at a high speed in its brushselection movement. During the upwa-'rd movement of the switch shaft aniutermittent grou-nd is connected to the circni-t forintermittentlyshunting down stepping relay 431 of the oiiice sender, over a circuitwhich may he traced from a junction point between the windings of relay431 and relay 318 (seque-nee switch cam 302),

through the upper left hand contact of sequence switch cam 302 (1?, to2'), conductor 329, brush selection segment 330 of the commutator 331,brush 332, conductor 333 and thence to ground through the upper righthand contact of sequence switch cam 306 (13 to 11).

After the initial closure of' the fundamental circuit through thewinding of relay 318 and the windings of sender steppingrelay 431, inresponse tothe intermittent shunting` of the windings of the steppingrelay 431, the stepping relay 431 in the well known manner causes thesuccessive operation of the counting relays of the sender until theswitch shaft 327 has moved upwardly to such an extent as to satisfy thesender when the relay 432 of the sender energizes, opening thefundamental circuit.

Relay 313 of the final selector switch thereupon deenergizes and at itsright hand armature and front contact opens the energizing circuit ofthe up drive magnet 326 to arrest the upward movement of the switchshaft and at its right hand armature and back contact closes a circuitfor driving sequence switch 300 out of position 2 and into position 3,this circuitextending from grounded battery through the winding of thedriving magnet of sequence switch 300, upper left hand contact ofsequence switch cam 312, right hand armatureand back contact of relay318 and thence to ground at the upper contact of A set of brushes,V

sequence switch cam 308. assumed to be the brushes shown, correspondingto the setting of the sender has now been positioned with relation tothev tripping fingers on the tripping spindle 334, so that upon thelater energization of the tripping magnet 335 and the subsequent upwardmovement of the switch shaft this set of brushes will be tripped f orengagement with the bank of 100 terminals with which this brush isassociated. To cause the tripping of this set of brushes, the trippingmagnet 335 is energized over a circuit extending from grounded battery,through the winding` of tripping magnet 335 and thence to ground at thelower left hand contact of sequence switch cam v306 as soon as sequenceswitch 300 reaches position 3.

When sequence switch 300- reaches position 3, the energizing circuit ofrelay 318 is again established over the fundamental circuit aspreviously described and relay 318 and stepping relay 431 `of the oflicesender energize. Relav 318 upon energizing again closes the previouslytraced circuit for driv-I ing sequence switch 300 out of position 3 andinto position 4. With sequence switch 300 in position 4, the previouslytraced circuit for the up drive magnet 326 is again established at theright hand armature and front contact of relay 318. Relay 318 alsoestablishes the previously traced locking circuit for itself extendingthrough its left hand armature and front contact for maintaining itselfenergized over the fundamental circuit after sequence switch 300 leavesposition 3 and opens the initial energizing circuit at -the lower righthand Contact of sequence switch cam 303. Upon the energization of thehigh speed up drive magnet 326, the switch shaft 327 is driven upwardlyin its group of tens selection movement and during the initial portionof this movement the selected set of brushes is tripped by the trippingspindle 334. During the remainder of the group selecting movement thetripped set of brushes travel upwardly in Contact with the terminals ofthe bank with which the brush. set is associated. During the groupselection movement of the switch shaft-fanv intermittentv ground isconnected to the fundamental circuit through the junction point(sequence switch cam 302) over a circuit extending through the upperleft hand contact of sequence switch cam 303 to 4), conductor 336, groupselection .segment 337, of the commutator 331, brush 338, conductor 333and thence to ground through the upper right hand contact of sequenceswitch cam 306.

In response to the intermittent connection of the shunt circuit-t0 thefundamental circuit, stepping relay 431 ofthe sender operates thecounting relays of thel sender in succession until the switch shaft 327has moved upwardly to such an extent as to satisfy the setting of thesender when relay 432 of thel sender is energized to open thefundamental circuit. As soon as the fundamental circuit is opened, relay318 deenergizes opening the circuit of the up drive magnet 326 to arrestthe upward movement of the switch shaft with the tripped set of brushesin engagement with the lowermost set of terminals in the selected group.Relay 318 also closesthe circuit previously traced for driving'sequenceswitch 300 out of position 4 and into position 5. In position 5 thefundamental circuity extending through the lwinding of stepping' relay431 of the sender and the left hand winding of relay 318 is againestablished and relay 318 upon energizing closes the previously tracedcircuit for driving sequence switch 300 out of position 5 and intoposition 6 and the previously traced locking circuit for itself which ismaintained after sequence switch 300 reaches position 6.

Upon reaching position 6 a circuit is established for the low speed updrive magnet 339 which circuit may be traced from grounded battery,through the winding of magnet 339, lower right hand contact of sequenceswitch cam 307, conductor 323, right hand armature and front contact ofrelay 313 and thence to ground at the upper'conllUV tact ot sequenceswitch cam 308. The low speed up drive magnet 338 upon energizingpresses the` depending portion ot the switch shaft 32.7 against theconstantly rotating low Y' roll-er 340 thereby causing the upmovement ofthe switch shaft in its units selection movement, iuring this up wardmovement of the switch shaft an interiittent ground is connected to thejunction point (sequence switch cani 302) in the fundamental circuitbetween the winding of sender stepping' relay 431 and the winding otrelay 313. over a circuit which niay be traced troni the upper lett handcontact ot sequence switch cani 302 to con ductor 32S), centeringportion of connnutator segment 330, brush 332, conductor and thence toground through the upper right hand contact of sequence switch caro 306.

in response to the intermittent connection of the above traced shuntcircuit to the Ytunn dainental circuit,y the stepping relay 431 of theotiice sender is intermittently operated to operate the counting relaysot the sender in succession until the switch shatt 327 has inovedupwardly to such an extent as to satisfy the setting o1 the sender, whenrelay 432 ot the sender energizes to open the tundan'iectal circuit.1When the undaincntal circuit is opened, relay 318 deenergizes, openingthe circuit ot the up drive magnet 339 to arrest the upward movement ofthe switch shaft, and closes the previously traced circuit drivingsean-,ence switch 300 out of pos i 6 into position Relay 313, however,does not deenergize until the selected set oi"- brushes are properlycentered upon the selected set ot baul; terniinals, since it ismaintained energized over the shunt circuit previously traced throughthe centering portion oi' the conaniutator seg nient The brushes of thefinal selectoix 350 have now been positioned upon e ininals of theholding cord circuit 200, the number ot which was transmitted to thecordless operator by the toll operator the toll switching center. YYWhensequence switch 300 reaches position 0 a circuit is closed forre-energizing relay 318, which circuit may be traced from grounded batLry through the right hand contact ot sequence switch cani 304 (1 to 10)the lett hand winding ol" relay 313, lower lett hand and upper righthand contacts ot sequence switch cani 310 and thence to ground at thelett hand armature and front contact of relay 321. Relay 318 uponenergizing closes a locking circuit for itself extending from groundedbattery, through its lett hand winding, .lower lett hand Contact ofsequence switch cain 310, left hand armature and f-t of relay 318 andthence to ground tnr u. is. til@ upper contacts of sequence switch canif This locking circuit switch tuin will be maintained through position10 of sequence switch 300. Relay 318 upon energizinp" also closes thecircuit as previously tr :ed for driving sequen-C'e switch 300 out otposition 9 and into position 12. Upon reaching position 10, a newholding circuit is established for relay 318 extending from groundedbattery, right hand winding of relayv 318, lower left hand contact ofseounice switch cani 315., right hand armature and front contact otrelay 318 and thence to ground at the upper right hand contact otsequence switch cani 308.

Upon reaching position 11 sequence switch 300 established a new holdingcircuit ior relay 318 extending troni ground, through the winding ottest relay 324, conductor 341, upper right hand contact of sequenceswitch cani 302, lower right hand contact of sequence switch cain 303,lett hand winding of relay 318, upper left hand contact of sequenceswitch cam 310, left hand armature and 'front contact of relay 318,le'l't hand contacts of sequence switch cani 313, test brush 342, andthence over bank tern'iinal 343 and winding oi"- sleeve relay 209 ot theholding cord circuit to ground. Since now the hold,- ing circuit ofrelay 318 extends :troni ground through its lett hand winding` and thewind ing of relay 209, to ground, relay 318 will be come deenergized assoon as sequence switch 300 leaves position 11 and neither relays 324nor 209 will energizeV at this time. When, therefore, relay 318deenergizes it closes a circuit Jfor driving sequence switch 300 out oitposition 12 and into position 13, this circuit eftending troni groundedbattery, inagnet 300, through the upper left hand contact ci sequenceswitch cani 312, right hand armature and back contact ot relay 318,lower right hand contact ot sequence switch cani 308 (12) and thence toground at the lett hand armature and front Contact of re- 321` Uponreaching position 13, a circuit established over the lower contacts ofsequence switch cani 309 and the left hand arincl ture and front Contactot relay 321 for drifing sequence switch 300 out of position 13 and intoposition 14 and in position 14 a circuit is established as previouslytraced through the winding of the driving magnet oi". sequence switch300.l right hand armature and back contact of relay 318, and thence toground at the upper Contact of sequence switch cani 308 tor drivingsequence switch 300 into the talking position 15, in which position thetrunk conductors 317 and 319 are connected respectively to the brushes352 and over the lower contacts of sequence switch Cain 302 and theupper contacts ot sequence switch cam 305.

As soon as sequence switch 300 reaches p0- sition 15 a circuit isestablished over the .test brush 342 and the sleeve conductor ofthe cordcircuit y200 for energizing the sleeve icc relay 209 of the cordcircuit. This circuit may be traced from grounded battery, through theleft hand contact of sequence switch cam 304, the lower contacts ofsequence switch cani 813, test brush 842, bank terminal 343, sleeveconductor 215 and thence to ground through the winding of sleeve relay209. Relay 209 energizing in this circuit closes a circuit for rela?,7210 extending from grounded battery, winding of relay 210 and thence toground throughV the right hand armature and front contact of relay 209,and at its left hand armature and back contact opens the circuitpreviously traced through the toll supervisory lamp 211 for giving thespecial operator a signal that the holding circuit has been seizedthrough selector switches from the cordless position. Relay 210 uponenergizing disconnects the windings ot relay 208 from the strands of theholding cord circuit and establishes a direct metallic connection fromthe tip and ring conductors 317 and 819 at the final selector switch.Relay 210 at its right hand armature and front contacts connects thewinding of slow to release ringing trip relay 216 through the backcontact and left hand armature Vof relay 214 to the back contact andright hand armature of relay 201, but since relay 201 is at this timeenergized, this circuit is without effect.

As soon as sequence switch 300 of the final selector switch 350 leftposition 81/2 tollowing the units selection movement of the switch, thecircuit previously traced over the bank terminal 449 and brush 451 oithe cordless incoming selector switch, through the lower contact ofsequence switch cain 415` (11) and thence over lead 456 to the cordlessoperators sender is opened at sequence switch cam 305 of the finalselector switch and the sequence switch associated with the sender isthereupon advanced into position 10., A circuit is now established foradvancing sequence switch 400 of the incoming selector switch out otposition 11 and into position 12c This circuit may be traced fromgrounded battery through the Winding of the driving magnet of sequenceswitch 400, lower left hand contact of seduence switch cam 411 andthence to ground through sequence switch cam 427. As soon as sequenceswitch 400 leaves position 11, the circuit previously traced throughlamp 429 and interrupter 430 is opened at the lower lett hand contact ofsequence switch cam 404 and the llickering signal which was produced bythe lamp 429 during the setting of the selector switches is stopped todenote to the operator that selection is completed, andl both lamps 423and 429 are then connected into a circuit in which both lamps burnsteadily. This circuit may be traced from grounded battery, throughlamps 423 and 429, lthe right hand contacts of sequence switch cam 404and thence to ground through the contacts of sequence switch cani 407.

As soon as sequence switch 400 reaches position 12, if at this time theoperator at the. switching center Y has made connection by her cordcircuit 108 with the assigned trunk7 relay 421 will be energized overtrunl; line 416 and a circuit'is established torrelay 422 which may betraced from grounded,"

t-act of sequence switch cam 406, right hand armature and front contactof relayu 422 and thence to ground atthe lett hand contact vof sequenceswitch cam 407. lVith sequence switch 400 in position 14, the armaturesoi ringing relay 457 are connected overI cams 414 and 415 to the tip andring brushes 452 and 451 of the incoming selector switch and thence overthe circuitestablished .through the brushes of the final selectorswitch, the conductors 220 and 217 oit the holding cord 200, tip andring conductors of the trunk circuit 108 and thence to the line of thecalling subscriber. The toll operator at switching. center Y may nowconverse with the calling subscriber and instruct him to restore hisreceiver to its switch-hook until he is recalled after the successfulextension of the connection to the desired line,

rllhe toll operator after being assured th at a connection has beenestablished,I between her cord circuit and the calling subscribers lineproceeds to obtain the assignment of a toll line 109 extending to theexchange'in which the desired line B terminates After receiving' anassignment of the toll line she then proceeds to connect the kcallingplug of hercord circuit 108 with the jack of the toll linet .-4.connection troni the toll line 109 is then established through the tollop-V erators position at the distant exchange and through theterminating operators7 position ot' the oiiice-Z of such exchange to theline ot the desired subscriber B.

The operator at the toil switching position now applies ringing currenttoI the trunk 416 for recalling the calling subscriber, and ring downrelay 458 is ener gized over a. circuit extending from the tin conductorof the cordless trunk circuit 416, through the upper right hand windingof repeating coil 419. through condenser 479, winding of relay 458,lower right hand Windf ing of repeating coil 419 and thence over thering' conductor ot the trunk 416 to the toll switching operat-orsposition. Relay 458 in responding' to the ringing current, closes acircuit tor relay 420 extending; from grounded battery, right hand winding` oit rew lay 420, armature and iront contact ot relay 458 andthence to ground through the winding ot ringing relay Relays 420 and 457both energize in this circuit, relay 420 disconnecting the windings ci'relay 421 from the conductors ot the trunk circuit 410 and maintainingrelay 421 energized over a circuit extending from grounded batterythrough the lett hand winding' of relay 421 and thence to ground throughmake contacts ot the right hand armature ot relay 420. Relay 457 uponenergizing attracts its armatures for connecting a source ot ringing'current 459 and ground to the ring and tip brushes 451 and 452respectively oi the incoming` selector switch. Ringing' current is thusapplied to the line of the calling; subscriber over a circuit whichv maybe traced from the source ot ringing current 459, lower armature andfront contact of relay 457, the upper contact of sequence switch cam415, brush 451, bank terminal 449,7`conductor 819, upper vcontactssequence switch cam 305 brush 353 and bank terminal 357 ot the finalselector switch 350, conductor 217 ot the holding cord circuit 200,inner lett hand armature and front cont-act of relay 210, conductor 218,ringy contacts of plug P and jack d, ring' conductor of trunk circuit103, lowermost brushes ot the selector switch 101 and line switch 100through the bell and condenser oi the calling subscribers station A,upper brushes ot line switch 100 and selector switch 101, tip conductorof trunk 10?` tip contacts of jack J and plug l?, conductor 219, outerlett hand armature and fronti contact of relay 210, conductor 220, bankterminal 359 and brush of the tinal selector switch 350, lower contactsof sequence switch` cam 302. trunk conductor 317, bank terminal 450 andbrush 452 of the incoming selector switch 41S, upper contacts otsequence switch cam 414 and thence to ground at the make contacts cgtthe upper armature of relay 457.

'When the calling subscriber responds to the application of ringingcurrent by removing his receiver trom its switch hook during the periodwhen ringing relay 457 ,isdeenergized, a circuit is establishedaspreviously traced trom the substation of the calling line, through thewindings oi' supervisory relay 461 and this relay energizes, closing acircuit from grounded battery, through the left hand winding ot relay420, armature and front contact of relay 461 and thence to ground at thearmature and iront Contact of relay 421. `When relay 420 respondsfollowing the operation of relay 461,

relay 421 is again disconnected tromthe conductors oit trunk circuit 416causing the operation ot a supervisory signal at the toll operatorsposition at the switching center Y to denote to the toll operator thattlc calling subscriber has responded to the application of ringingrcurrent and is ready to converse with the subscriber B in the distantexchange.

lWith sequence switch 400 in position 14 and relay 422 held energizedthrough the circuit previously traced to ground at the armature andiront contact of relay 421, the circuit for lamp 429 is maintained untilconversation is completed. rlhis circuit may be traced trom groundedbattery through lamp 429, the lower right hand and upper left handcontacts of sequence switch cam 404, lett hand armature and irontcontact ot relay 422 and thence to ground through the lett hand contactsof sequence switch cani 405. Lamp 423 is not at this time illuminated.

The subscribers A and B are now connected to a circuit over whichconversation' may take place, which circuit may be traced in Fig. 1through the brushes or" line switch 100, brushes ot selector switch 101over the trunk circuit 103, holding cord circuit 200,

brushes oi' final selector switch 350, brushes ot cordless selectorswitch 418, trunk 416, the toll cord circuit 108 at the toll switch-,ing center Y, toll line 109 and thence over the cord circuit in theoiiice Z of the distant exchange, talking rcurrent being supplied to thecalling subscriber through the windings of relay 461 of the incoming'selector switch at the cordless operators position 0 and talking currentbeingl supplied to the called subscriber from the terminating operatorscord circuit in the otliee Z.

rll-he operator at the switching center Y has full supervision ot theconnection from the time she receives the assignment of the cordlesstrunk circuit and neither the special A operator nor the cordlessoperator need give further attention to the connection until it becomesnecessary to take it down. Thu-s, the special A operator and thecordless operator are tree during` the setting up and continuance oi thetoll connection to employi the otherapparatns at their respectivepositions in the most economical manner,

.li/Vere it necessary tor the special operator to remain in ou aconnection until after the termination oi conversation over the tollconnection, it. would practically result in the tying up ot all oi' herapparatus 'for that period, as on toll connections it is necessary forthe supervising operator to note the time elapsing during theconversation tor assessment purposes.

Upon the termination ot the conversation both subscribers restore theirreceivers to their switch hooks, the restoration et the reltery throughlamp 423, rightrhand contact Voi: sequence switch cam 407, right handceiver to the switch hook at the called substation B causing in the wellknown manner the operation et supervisory signal at the Athe circuitotrelay 461 which upon deenergizing opens-the circuit oi relay 420, thusreconnecting the windings ot relay to the conductors of' the trunkcircuit 416, which thereupon in the well known manner causes theoperation oit a supervisory signal at the switching `center Y, to informthe toll operator at that position that the conversation is completedand that she may take down the connection at her position.

As soon as she removes the answering plug or her cord circuit V108 fromthe jack ot the cordless trunk circuit 416, the relay 421 becomesdeenergized and opens the circuit ot relay 422, which upon deenergizingopens the circuit previously traced through lamp 429 and closesvcircuits for flashing both lamps 423 and 429. The circuit ot' lamp 423may be traced from grounded batarmature and back contact ofrelay 422 andthence through the right hand contact of sequence switch cam 408 andinterrupter 462 to ground. |The circuit ot lamp 429 may be traced tromgrounded batteryi through lamp 429, lower right hand and upper le'r'thand contacts of sequence switch cam 404, lett hand armature and backcontact ot relay 422, upper lei't hand and lower right hand contacts ofsequence switch cam 408 and thence to ground through interrupter 462.The operator at the cordless position in response to the flashing oflamps 423 and 429 operates the disconnect key 463. A circuit is nowestablished which may be traced from grounded battery through thewinding ot the driving magnet of sequence switch 400, lower right handcontact of sequence switch cam 411, and thence to ground through thecontact of key 463 for driving sequence switch 400 out of position 14and into position 18. A. circuit is now established for the down drivemagnet 464 which may be traced from grounded battery through the windingoit' magnet 464 and thence to ground through the right Vhand contact otsequence switch cam 413. Magnet 464 upon energizing presses thedepending portion of the switch shaft 434 against ythe constantly.rotating down drive roller 465 thereby causing the downward movement otswitch shaft 434 into its normal position.

When the switch sha-ft reaches its normal position a circuit isestablished torldriving sequence switch 400 into its normal positionwhich circuit may be traced Jfrom grounded bank terminal 448 conductor325, right hand armature and Jfront contact of relay 321,

armature and backcontact of relay 324 to grounded battery through theright hand winding of relay 321 is opened and relay 321 deenergizes.Upon deenergizing this relay connects ground potential to the sleeveconductor 325 from ground through the right hand contact of sequenceswitch cam 314, right hand armature and back contact ot relay 321, forthe purpose ot holding the circuit extending to the final selector 350busy until the iinal selector switch is fully restored and sequenceswitch 300 ot the final selector has returned to Vits normal position.At its right hand armature and back contact relay 321 closes a circuitextending from grounded battery through the right hand winding ofrelay318, the upper contacts of sequence switch cam 309, and thence toground through the armature and back contact of relay 321. Relay 318upon energizing, establishes a circuit for driving'se- Y quence switch300 out ot position15 and into vposition 16, this circuit extending fromgrounded battery, winding of ldriving niagnet of sequence switch 300,lower lett hand contact of sequence switch cam 312, right hand armatureand Jrontcontact of relay 318, and thence to ground through the uppercontact ot sequence switch cam 308. When the sequence switch reachesposition 151/2, relay 318 dee'nergizes and at its right hand armatureand back contact closes a circuit for driving sequence switch 300 out ofposition 16 and into position 17. ThisV circuit may be traced fromgrounded battery through the winding ot the driving magnet of sequenceswitch 300, upper left hand contact otY sequence switch cam 312,rightrhand armature and back contact of relay 318 and thence to groundthrough the upper contact ot sequence switch cam 308;

A circuit is now establishedA for driving sequence switch 300 out ofposition 17' and Vinto position 18 extending from grounded batterythrough the winding of driving magnet of sequence switch 300, lower letthand and upper right hand contacts of sequence switch cam 309 and thenceto ground at the left hand `armature and back contact oit' relay 321.Vith sequence switch 300.in position 18,

a circuit is established for down drive magnet 344 which may be tracedfrom grounded battery through the winding of magnet 344, lower contactof sequence switch cam 311, upper left hand contact of sequence switchcam upper right hand contact of sequence switch cam 306, and thence toground. Magnet 311 upon energizing presses the depending portion of theswitch shaft 327 against the constantly rotating down drive roller 845,thereby moving the switch shaft 327 down into its normal position. `Whenthe switch shaft reaches normal position a circuit is closed for drivingsequence switch 300 out of position 18 and into its normal position 1.This circuit may be traced from grounded battery through the winding ofthe driving magnet of sequence switch 300, upper right hand contact ofsequence switch cam 312, conductor 346, normal segment 3&1? ofcommutator 331, brush 838, conductor 333 and thence to ground throughthe upper right hand' contact of sequence switch cam 306. The circuitsor' the final selector switch are now in normal condition.

is soon as sequence switch 300 left position 16%, battery potential was'disconnected at sequence switch cani 318 from the circuit previouslytraced through brush 342, bank terminal 3&3, sleeve conductor 215 andthe winding of relay 209. Relay 209 thereupon deenergizes, opening thecircuit of relay 210. 7Upon the deenergization ont relay 209 the circuitof the toll supervisory lamp 211 isagain established from grounded bat#tery, through lamp 211, the left hand armature and back contact of relay209 and the right hand armature and front contact of relay 201. Thedeenergization of relay 210, again connects the windings of relay 20S tothe strands 218 and 219 of the cord cir cuit 200, but since the callingsubscriber has restored his receiver to its switch hook relay 208 is notenergized. However, since relay 209 is at this time deenergized, acircuit is established for the supervisory lamp 207 which may be tracedfrom grounded battery through lamp 207, left hand armature and f'rontcontact of relay 201, armature and baclr contact of relay 208 and thenceto ground at the right hand armature and bach contact of relay 209. Inresponse to the illumination of lamps 20T and 211 the open ator atposition 0 removes the plug P 'from the jack J. The circuit previouslytraced through relays 201 and 2041 is now opened, relay 201 deenergizingto open the circuits of lamps 207 and 211, andrelay 2041 deenergizing toopen the circuit of relay 205 which in turn disconnects ground potentialfrom sleeve conductor 206 of the trunk circuit 103 thereby Yinitiatingthe restoration ot the district selector Vswitch 101 and' line switch100 of' the full mechanical office X.

All apparatus which has been employedin the connection is now restoredto normal condition.

1i through error a calling subscriber in the full mechanical ofhce' setsa final selector switch upon the terminals of a holding" cord circuit200 which'is not in use at the special operators position 0, thecircuits of the holding cord will function in the following manner whenthe holding cord'is seized by the final selector switch Upfon theengagement of the test brush 3/12 of the: final selector switch with thebank terminal 3113 of the holding cord 200,'with the sequence switch 300of the final selector switch in position 15, a circuit as previouslytraced over conductor 215 and through the Winding'fof' relay 209 isestablished and relay 209 becomes energized in this circuit. Uponenergizing, relay 200 closes the previously traced circuit for relay210. Since the cord circuit is not in use, plug P is not in jack J andrelay 201 is not therefore energized.

lilowever, upon the energization of relay 209 a circuit is establishedfor the' toll lamp 211 which may be traced from grounded battery,through the lamp, left hand armature and front contact of relay 209 andthence to' ground at the righthand armature and back contact oi relay201. Relay 210 upon energizing closes a circuit for slow to release re-`lay 216, which may be traced from grounded battery through the windingof relay 216, right hand armature and front contact of relay 210, lefthand armature and back contact of relay 21-1 and thence toground at theright hand armature and back contact of relay 201.

The operator noting the illumination of lamp 211 presses the listeningkey 212 to con nect her telephone set to the seized holding' cord 200and thereby establishes a circuit for relay 211, which may be tracedfrom grounded battery through the left hand winding o1 relay 2111 andthence to gro-und at the contacts 213 of the key 212. The operation ofrelay 214, opens the circuit of relay 216 and at its lett hand armatureand front contact connects ground through resstance element 221,armature and front contact of relay 216, ring' conductor 217 of the cordcircuit 200, during a period meas'- ured by the time required for relay216 to release for the purpose of tripping ringing current at theincoming selector switch over which the connection has been established.The operator, upon the termination of' the application of ringingcurrent, may then converse with the calling subscriber and in form thesubscriber that he has made an erroneous connection.

1f the cordless operator through error sets' the final' selector switch350 upon the terminals olf a holding cord 200, Which has not'. beentaken for use, the holding cord circuit functions in the mannerpreviously described except that the connection of ground to the ringconductor of the cord circuit does not cause the tripping of the ringingcurrent at the cordless operators position, since ringing current ismanually applied through the operation of a ringing key at the tooloperators position. Vthen the operator at the special operators position0 becomes connected to the holding cord circuit 200, through contacts ofkey 212 a circuit is then established for the relay 461 at the cordlessincoming selector switch which in the manner previously describedoperates the supervisory signal atthe toll operators position. `Thespecial operator may Vthen converse with the toll operator and transmitlto her-the information that the connection has been inaccurately madeand may also transmit to the operator the correct number of the holdingcord which she has employed. In the case o-f an erroneous connection thecircuits at the cordless operators position and the final selectorswitch 350 which has been employed are restored to normal condition inthe manner previously described.

When the cordless incoming selector 418 is hunting for an idle finalselector switch which has access to the desired holding cord 2,00, itmay happen that all idle final selector switches are at the time busy.The incoming selector switch will then be driven to an overflow positionimmediately above the selected group of trunk circuits extending to thedesired group of final selector switches. lith the switch in theoverflow position and the sequence switch 400 in the trunk huntingposition 9, relay 422 deenergizes closing at its right hand armature andback ,contact a circuit for driving sequence switch 400 out of position9 and into position 11. This circuit may be traced from grounded batterythrough the winding of the driving magnet of sequence switch 400, lowerleft hand contact of sequence switch cam 406, right hand armature andback Contact of relay 422 and thence to ground at the left hand contactof sequence switch cani 407. ldith sequence switch 400 in position 11and the selected set of brushes in the overflow position, shaft brush437 is in contact with an overflow segment of comniutator segment 438and circuit is therefore established for advancing sequence switch 400out of position 11 and into position l2. This circuit may be traced fromgrounded battery, through the winding of the driving magnet of sequenceswitch 400, upper right hand contact of se.- quence switch cam 411,conductor 467, commutator segment 438, brush 437, and thence to groundat the up-per contact of sequence switch cani 413. Since at this timerelay 421 is energized over the cordless` trunk circuit 416 a circuit isnow effective for energizing relay 422, which circuit may be tracedfrom. grounded battery, left hand winding of relay 422, lower left handcontact of scquence switch cam 402, upper right hand contact of sequenceswitch Vcani and thence to ground at the armature and front contact ofrelay 421. Relay 422 upon energizing closes a circuit for drivingsequence switch 400 out of position 12 and into posi- This circuitextends from groundtion 14. ed battery, through the winding of thedriving magnet of sequence switch 400upperV left hand contact ofsequence switch cam 406, right hand armature and front contact Y ofrelay 422 and thence to ground at the left hand contact of sequenceswitch cam 407. A circuit is now effective as previously traced over theupper right hand contact of sequence switch cam 411 and the overflowsegment of commutator segment 438 for Ladvancing sequence switch 400 outof position 14 and-into position 17. A circuit is 'now effective forconnecting the supervisory for advancing sequence switch 400 out .of y

any position between positions 4 and 9 into position 10 for arrestingthe upward movement of theV switch shaft thereby preventing` injury toits mechanism. This circuit.

may be traced from grounded battery through the winding of the drivingmagnet of sequence switch 400, upper right hand contact of sequenceswitch cam 406, (2' to 9) conductor 468, telltale segment 469 of thecominutator 439, brush 455,` conductor '136 and thence to ground eitherthrough he upper contact of sequence switch cam 413 in positions 10 to8, or to'ground through the upper contacts of sequence switch cani 412in position 9 and thenceV I.

through therright handr armature and' front contact of relay 422 and theleft hand con-- tact of sequence switch cam 407. In the tell taleposition of the switch the usual tell tale signals are lighted onthefruine upon which the switch is located for the purposeof attractingthe attention of the switchboard attendant.

That is claimed is: Y

1. In a telephone exchange system, an originating office, a secondol'lice, a trunk line extending between said oiiices, a subscribers lineterminating in said first ofiice, means for extending a connection fromsaid subscribers line to said trunk line, and means at said first officefor maintaining another connection with said subscribers line after saidfirst mentioned connection has been disestablished.

2. ln a telephone exchange system, an originating oiiice, a secondoi'tice, a trnnl; line extending between said offices, a snbscribersline terminating in said iirst office, means :tor extending a connectionfrom said subscribers line to said trunk line, and a holding cordcircuit at said first oiiice for maintaining another connection withsaid subscribers line, after said first mentioned connection has beendisestablished.

3. ln a telephone exchange system, an originating ofiice, a secondofiice, a trunk line extending between said ofiices, a subscribers lineterminating in said first oiiice, means for extending a connection fromsaid subscribers line to said trunk line including selectorswitclies andan operators cord circuit, and a holding cord circuit at said operatorsposition for maintaining another connection through said selectorswitches with said subscribers line after said first mentionedconnection has been disestablished by the disconnection of said firstmentioned cord circuits. Y

4. ln a telephone exchange system, an originating ofiice, asecondoflice, a trunk line extending between said offices, a subseribers lineterminating in said first oiiice, means for extending a connection fromsaid subscribers line to said trunk line including selector switches andoperators cord circuit, and a holding cord circuit at said operatorsposition i'i'or maintaining another connection through said selectorswitches with said subscribers line after said first mentionedconnection has been disestablished by the disconnection of said firstmentioned cord circuit and after said subscriber has returned hisreceiver to its switch hook.

lin a telephone exchange system an originating otiice, an intermediateoffice, a terminating office, a trunk line extending between said firstnamed ofiices, a calling subscribers line terminating in said firstoliice, a subscribers line terminating in said terminating oiiice, meansfor extending a connection from said calling subscribers line to saidtrunk line, means at said intermediate ofiice for extending a connectionto said terminating oiiice, means at said first ofiice for maintaininganother connection with said subscribers line after said lirst mentionedAconnection has been disestablished, and means for extending aconnection fromV said intermediate office to said holding means wherebysaid subscribers lines are interconnected through said holding means,said last named means and said connection extending means of saidintermediate office.

6. lfn a telephone exchange system, an originating oiiice, anintermediate office, a

terniinating ofiice, trunk line extending between said first namedoffices, a calling subscriberis line terminating in said first otiice, acalled subscribers line terminating in said terminating oflice, anopeiators position in each of said otiices, means for extending aconnection from said calling line to the operatoifs position in saidirst oiiice, means for establishing a call circuit over said trunk linebetween the operators positions in said first named oiiices, means forextending a connection between the operators position of saidintermediate oiiice and said called line, a holding cord at theoperators position of said iirst oiice for maintaining anotherconnection with said calling line after said first mentioned connectionwith said calling line has been disestablislied, and means for extendinga connection from the operators position of said intermediate oh'ice tosaid holding cord.

7. In a telephone exchange system, an originating ofiice, anintermediate ofiice, a terminating otiice, a trunk line extendingbetween said lirst named offices, a calling subscribers line terminatingin said first oiiice, a called subscribers line terminating in saidterminating otiice, an operators position in each of said oiiices, meansfor extending a connection from said calling line to the operatorsposition in said first office, means for establishing a call circuitover said trunk line between the operators positions in said first namedctiices, means for extending a connection between the oper-- atorsposition of said intermediate oiifice and said called line, a holdingcord at the operators position oi said first oiiice for maintaininganother connection with said calling line after said first namedconnection with said calling line has been disestablished, and selectorswitches 'for extending a connection baci: from the operators positionot' said intermediate otiice to said holding cord.

8. In a telephone exchange system, originating office, an intermediateofiice, a terminating office, a trunk line extending between said rstnamed oiiices, a calling subscribers line terminating in said firstofiice, a called siibscribers line terminating in said terminatingoffice, an operatcrs position in each of said offices. means forextending a connection from said calling line to the operators positionin said iirst oiiice, means for establishing a call circuit over saidtrunk line between the operators positions in said first named ofiices,means for extending a connection between the operators position of saidintermediate office and said called line, a holding cord at theoperators position ot said first oiiicc for maintaining` anotherconnection with said calling line aitei said liist mentioned connectionWit-h said calling line has been disestablislied, supervisory meansassociated With said hold-- ingcord, means i'oi extending a connectionfrom the operators position of said inter mediate othce to saidlioidingcoi-d, and means operative upon the. establishment of said latterconnection to transt'er supervision iroii'i said holding cord to theoperators position at said intermediate otiice.

9. ln a teiephone exchange system, an originatinel o an intermediateo'iiice, a tercnice, a tilinli line extending between i id iiist namedo'ices, a calling subscrioers line tei'iiiiiiating in said first oiiice,a called snbscribefs line terminating in said tern'iinating tance, anoperatoi"s position in each ot said oii'icesgneans for extending aconnection trom said calling line to the operator-s position in saidi'iist office, means for establishing a call circuit over said trunkline between the operators positions in said lii'st named oiiices, meansfor extending a connection between the opera-V tors position oi saidintermediate cnice and said called line, a holding cord at the operatorsposition ot said iirst oti'ce for maintaining aiiot-her connection Withsaid calling line after said iii-st mentioned connection With saidcalling line has been disestablished, a signal associated with saidholding cord, means -for extending a connectionY from the operatorsposition of said intermediate otiice to said holding cord, and meansoperative upon the establishment of said latter connection to operatesaid signal it said holding cord is not at the 'time in use.

l0. In a telephone exchange system, an originating office, anintermediate offlice, a terminating office, a trunk line extendingbetween said first named oiiices, a calling subscribers line terminatingin said first ofiice, a called subscribers line terminating in saidterminating oiiice, an operators position in each of said oiiices, meansfor extending a'connection from said calling line to the operatorsposition in said first ofiice, means for establishing a call circuitover said trunk'line between the operators position in said first namedofhces, means for extending a connection between the operators positionof said intermediate oiiice and said called line, a holding cord at theoperators position of said iirst oiiice tor maintaining anotherconnection with said calling line after said first mentioned connectionwith said calling line has been disestablished, a signal associated withsaid holding cord, means for extending a connection from the operatorsposition of said intermediate oiiice to said holding cord and forapplying ringing current to said calling line, means opmeans under thecontrol of the operator for Yestablishing a connection between herposition and said second oiiice, and means at said iirst oiiice tormaintaining another connection with said snbscribers line after saidiiist mentioned connection has been disestablislied. y Y

i2. ln a telephone exchange system, an originating oiiice, `a secondoiifice, an operators position in said iirst o1'i`ice,a subscriberlsline terminating in said first office, means for extending a connectionfrom said subscribers line to said operators position, means under thecontrol of the operator for establishing a connection Vbetween herposition aiidvsaid second oiiice, and a holding cord circuit at saidiirst otiice for maintaining another connection With said siibscribers.line after said first mentioned connection has been disestablished.y

i3. ln a telephone exchange system, the method oi establishing tollconnections between subscribers lines in Widely separated oiiices whichconsists in extending a connection from a calling subsciibersrline in anloo originating otlice to a special operators posi- Y tion, establishinga connection with such extended line and obtaining the designation ofthe line desired, establishing a holding connection With siich extendedline, transmitting the designation of the line desired c and thedesignationl of the holding connection to a toll switching center,disestablishingthe initial connection With the extended calling linewhereby the special operator is freed for the performance of otherduties, building back a connection from the switching center to theextended calling line over the holdingl connection and extending suchbuilt back connection through the switching center to the desired line.

le. In a telephone exchange system, the method of establishing tollconnectionsrbetween siibscribei'slines in Widely separated offices whichconsists in extending a connection from a calling subscribers line in anoriginating office to a special operators position, establishing aconnection With such extended liiie and obtaining the designation of theline desired, establishing a holding connection with such extended line,transmitting the designation of the line desired and the designation ofthe holding connec-

